When failing over to the next server, RFC 3263 says the client should send a new request identical to the previous one but with a new Via branch ID, making it a new SIP transaction.
Checked 2026-10-02
If a failure occurs, the client SHOULD create a new request, which is identical to the previous, but has a different value of the Via branch ID
- Vendor
- not restricted
- Product
- not restricted
- Subsystem
- SIP DNS server location
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 3263, current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- RFC 3263: Session Initiation Protocol (SIP): Locating SIP Servers — RFC Editor / IETF · tier 1 standards and regulators · Section 4.3
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry
BibTeX
@misc{warmtransfer-claim-sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry,
title = {Troubleshooting SIP 408 Request Timeout and calls that get no response: source note sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry},
note = {Source note sip-408-timeout-troubleshooting-rfc3263-new-branch-on-retry, checked 2026-10-02}
}